1. Field of the Invention
The present invention relates to an apparatus and method for measuring the mass of molecules by quantitating the energy loss of directed particles. More specifically, the present invention provides a method and apparatus for direct quantitation of the amount of an applied material while remaining compatible with other methods of analysis, such as, for example, quantitating the elemental or isotopic content, identifying the material, or using the material in biochemical analysis.
2. State of Technology
Proteins are primary effectors created from genomic codes that provide fundamental structures, pathways, and regulations required in a living entity. Numerous methods exist to study proteins involved in all levels of life, from healthy cellular cultures to diseased humans. The totality of these methods are now subsumed under the rubric of “proteomics”, and the current state of the art in proteomics emphasizes identification of proteins and their post-expression modification using dimensional separation followed by mass spectrometry.
However, such protein molecules and other biological molecules, such as, but not limited to, DNA, or RNA or complexes of these, are difficult to quantitate without specific standards to compare the measured response of the unknown to the measured response of the standards. Specifically, protein quantitation with general standards has an error that can be as large as about 20%. Further analysis of proteins by other methods normally require an additional aliquot (i.e., an additional representative sample), which requires more protein and involves additional pippeting and dilution errors. Although qualitative detection of specific macromolecules can be achieved with mass spectrometry techniques currently available, the quantity of the molecules cannot be accurately determined with mass spectrometry because desorption and ionization varies between molecules and is affected by the matrix of the system.
Accordingly, a need exists for accurate and sensitive mass quantitation of applied amounts of molecules on substrates while remaining compatible with multiple non-destructive and destructive methods of analysis known in the art. The present invention involves a system and method to address such a need.